The movie opens in a flash back where we see the Man (Viggo Mortensen) in bed with his wife (Charlize Theron). The man wakes up to a sound and a glow coming from outside the window of their room. He walks to the window and looks out. In a hurry, he then runs into the bathroom where he begins to fill the sink and bathtub. His wife wakes up and comes into the bathroom and asks why he is taking a shower. He says, “I’m not taking a shower”. She then looks outside to see what he saw. The scene then cuts to the present where the man is walking with his son down a snow-covered road.

As the Man and his son are walking, we hear a narration by the Man explaining that he does not keep track of time anymore. He further explains (in a very vague way) that a few years ago at 1:17, there was a bright flash in the sky followed by rumbling sounds and that was when time stopped. As the Man and his son walk and search abandoned cars, the narration continues. He then says that the sun has not come out for a long time; the weather is getting colder and greyer every day. He then says the things he fears the most are cannibals and hunger. They are walking to the coast and heading south to see if things are warmer and better there.

The Man and his son stop at a car in the road and make camp. While they sit in the car talking, we see that the Man has a pistol with 2 rounds in it and a shopping cart full of things they have collected. The two talk about the boys mother and we understand that she has died. The Man also explains to the son how to kill himself the right way with the gun, and the reason there are 2 bullets left are for one for each of them. The 2 fall asleep and the Man has a dream/flashback. In this flashback, we see the Man and his wife talking about killing themselves like the other families in the area. She says that if they are caught, they will be raped, killed and eaten. He says that she needs to be strong and stop talking about that. She says that they only have 2 bullets left and that they should use them now. The Man gets up to go to the kitchen in anger/sadness. The wife then looks down and we see that her water has broken and she is pregnant. She then starts to lose control and wants to kill herself before she has the child because she does not want to raise a child in this world. The Man talks her out of it and we see him helping her through labor. Right then the flashback ends as the man wakes up suddenly to the sound of a truck in the distance. He wakes his son and they run out of the truck they were sleeping in into the nearby woods, leaving the cart. They jump and hide in a ditch and leave the cart by the truck they were sleeping in. Through a nearby tunnel, a truck full of men drives down the road and stops by the Man’s cart. The men get off of the truck and start looking through the nearby woods for them. One stranger walks very close to the hiding Man and his son, and stops to urinate on a tree. He then sees the man and the son hiding and tells them to come to the truck because they have food. The Man is pointing the gun at the stranger and tells him to not look back at the people he came with and to come with them or he would shoot him in the head. He refuses and calls the Man a coward. Just then the truck starts and startles the Man and his son. The stranger then jumps down and grabs the son at knifepoint. The Man then shoots the stranger in the head, grabs his son and runs into the woods hiding over night avoiding the group who were looking for them.

The next morning, the Man and his son go back for the cart. Almost all of their stuff is gone, and as they are cleaning up the little that is left, we see a bloody pile of flesh on the ground and we get the idea that the men ate the stranger who was just shot. The Man and his son continue to walk. They stop and talk about different things. The son asks if they are still the good guys. The Man explains that they are always going to be the good guys, and they are carrying the “fire” inside together.

They stop at another truck to sleep, which is parked on top of a very high bridge. The Man and his son go to sleep. In the morning, the Man wakes up and walks to the edge of the bridge where he takes a wallet out of his jacket with a picture of his wife in it. He throws it over the bridge. We then get another flashback of the Man and his wife together with the son who is older now (almost as old as he is in the present). The wife says she is going to leave and the man begs her to stay another night. She blames the man for not letting her die earlier, refuses and walks outside without saying goodbye to the son. She takes off her jacket and outer clothing and walks off into the dark to die. The flashback is over and the Man is still at the edge of the bridge. He takes off his wedding ring and slides it to the edge of the bridge without pushing it over the side, and leaves it.

The two walk on and see a large house in the distance. After looking at it through binoculars, they decide to go into the home. In the main room, there is a pile of shoes about 5 feet high. The Man is very confused and goes into the kitchen where he sees a large door in the floor, which is locked. He pries the lock open and the two go down into the dark room. They hear something in the darkness and when they get close, a naked man comes into the light. The Man and she son get scared and try to leave. As they attempt to leave, the see an entire group of malnourished people sitting scared and naked in the dark. They franticly try to leave as another naked man grabs the Man and he has to fight them off. They get out of the cellar and push a table over the door. The son screams and out the window, we see another group of people walking to the home with weapons. We also see large vats with metal bloody hooks over them and we can tell that they are used for eating the people in the locked cellar. The Man and his son run upstairs and hide in a bathroom. The Man hears a woman say she is going upstairs to change. The Man gets his gun and puts it to his son’s head and gets ready to shoot him to protect him from the cannibals downstairs. As the woman makes her way upstairs, the naked people in the cellar break the door open and a large commotion breaks out. In the commotion, the Man and his son run out and quickly hide while the people in the home try to find them. They stay for a while and in the middle of the night they leave.

As they are walking, they find the neighborhood where the Man grew up and his old home. He walks through the home remembering the things of his past. The son wants to wait outside. While he is sitting on the porch, the son sees a boy in a room across the street. He runs to see them and starts chasing a boy about his age. The Man then comes running after him and will not let him go any further. The Man says he imagined the boy and they leave.

They come across another home on the road. They go through the home and see a man who died in his bed. They take a blanket and walk about. In the yard of this home is a pile of rubble. They look through the rubble and find a steel hatch which the Man pries open. They go into the hatch, which turns out, to be a bomb shelter stocked full of food. They eat; get a shave, the shower and make home in the new shelter. After 2 nights in the shelter, the Man wakes up coughing up some blood. They hear something from above the shelter and they both say it is a dog. The Man says they must leave because with a dog is people. They stock up food in a pull cart and head out the next morning.

As they are walking, they see an old man (Robert Duvall) walking. They approach him very carefully and see that he is no threat. The boy wants to bring him along and the Man says no, but he allows the old man to eat dinner with them. As they eat and talk, the old man says that he thought the boy was an angel and he never thought he would see a child again. They continue to talk and then go to sleep. The next day the Man and the son are on their way alone again.

While the Man and the son continue, they go into the woods and leave the cart because they see a series of wooden huts. As they walk closer, the Man sees a row of sticks in the ground with human skulls on them surrounded by piles of skulls on the ground. They turn to go away and they see a fresh pile of blood soaked snow and they both get scared. As they turn to run away, they see a woman and a child running as fast as they can from the woods across from them. Behind the woman is a group of cannibals chasing the woman and child. The Man and the son run into the opposite woods and in the background, we hear the woman and child get killed. The Man and the son run through the dead trees, when all of a sudden the trees around them start to fall down in a small earthquake. Multiple trees almost hit them and they take cover and hide for a minute and regroup. They check to see if it is clear and they escape to the road again.

The next day after they Man and son wake up from camp, we see the Man is growing sicker. They talk about how they are close to the ocean. The son asks if the ocean is blue and the man says, “It used to be”. They walk up a large sand dune and look at the brown ocean and beach, which is scattered with garbage and debris. They walk to the water and look at a crashed boat about 200 yards into the surf. The Man notices that the son is getting sick. They make a small tent and the Man says he is going to the boat to see if there is anything useful there, takes off his clothes and swims out to the boat. The son falls asleep. While the son is sleeping, we see a stranger with a knife walk up to the sleeping boy in the tent. The next shot is of the Man swimming back to shore with a flare gun from the boat. He puts on his clothes and goes running to his son. They have been totally robbed, but the son is not harmed. The thief took everything including the Man’s shoes. They start walking to try to catch the thief and get their belongings back.

As the Man carries his son, they see the thief with their cart in the distance. The Man takes the pistol and runs after the thief. He stops the thief who is holding only a knife. The Man instructs the thief to put the knife down. He does. The Man then tells him to take off all of this clothing and to put it in the cart. The thief is terrified and does everything he asks. The man puts his shoes back on and leaves the thief naked in the road. The son begs to leave him some clothing and the man says no. They go back to the beach where the son convinces the Man to leave the thief his clothing. They go back and try to find the thief who is nowhere to be seen. They leave him his clothing and a can of food in the road. The Man and his son continue walking.

They start walking through a street lined with homes. It is quite and they find a tin with a live bug inside. While it flies away, they both stare at it in amazement. Right then the Man gets shot in the leg with an arrow. They jump to take cover and the Man shoots another stranger in a window with the flare gun. We hear screaming from the room and the wounded Man goes running to see who is inside. He gets in the room where he sees a woman who is sitting over the stranger who shot him. The stranger has just been shot and killed by the flare gun. This stranger is dead and the woman is weeping. The Man leaves the woman and gets his son and belongings. They go get shelter and the Man takes the arrow out of his leg and uses a stapler to close the wound in his leg.

The Man and his son go walking back to the ocean and the man stops. He says he cannot pull the cart anymore due to his leg. They take a bag full of the food and they head to a sandy spot of the beach. The Man who is wounded and very sick lies down and they make a camp there. They fall asleep. While they are sleeping, the Man has a dream of his wife and his old life. The sun is shining, they make love and we see what life was like prior to the world ending. He wakes up to his son who is talking to him. The Man knows he is going to die soon, and he tells his son to continue on south. He says to remember things that he has taught him and to keep going like they have been. The son says he wants to die with the Man, and the Man says he cannot do it. He says that his whole heart is in his son and he has to go on. He then falls asleep and dies.

The son wakes up the next morning and sees that the Man has died. He cries and lays next to him for an entire day and night.

The following morning, the son wakes up. Looks at the Man, reaches into his jacket and takes his binoculars. He then covers the Man with a blanket, puts the pistol with 1 round left into his belt and he walk to the shoreline. In the distance, we see a stranger (Guy Pierce) walking toward the son. The son points the gun at him and is very scared. The stranger has a rifle but he is not aiming it at the son. The son asks him if he is a cannibal and the stranger says no. The son lowers the gun and the stranger kneels to talk to the son. The stranger asks the son who the man on the beach is and the son explains that it was his father. The stranger tells the son “you have 2 choices. You can come with us or you can stay here. If you decide to stay, you should stay off the road”. The son asks if he has any children. The stranger says that he has a boy with him and a girl. The son asks the stranger if he is a good guy and if he is “carrying the fire inside”. The stranger says that he is a good guy and says that the boy is a little freaked out. The boy asks how he can trust the stranger and the stranger says, “you cant, you just have to trust me”. The son then walks to his dead father and says I will do everything you taught me to do. He kissed him and covers him back up. As the son walks to the stranger, we see that he is with a woman (Molly Parker) and 2 children. The woman touches the son's face and says, “we have been following you and your father for a long time”. The boy sees that they also have a dog. She then continues to say, “You have nothing to worry about anymore. We are with you now. We are together”. As she touches his face, a tear rolls down her cheek and the screen goes black.